class Vnode {
  constructor(tag, data, value, type) {
    this.tag = tag && tag.toLowerCase();
    this.data = data; // 节点属性
    this.value = value; //文本内容
    this.type = type;
    this.children = [];
  }
  appendChild(vNode) {
    this.children.push(vNode);
  }
}
